You could set up a dynamic DNS updater. This will allow you to access your Android device using the same internet IP address no matter where you are. You will need an account with a dynamic DNS provider [1] and an Android SSH server that includes/supports a DNS update tool [2].

You will then be assigned a fixed IP address by the dynamic DNS provider, which you can use wherever you roam. Network limitations (technical or imposed) may still prevent you from access your device in some circumstances.